In modern agriculture, soil is often worked or conditioned prior to planting to ensure an optimum environment in which the seeds can germinate and grow. The desired result is a high crop yield. "Conditioning" of the soil generally refers to breaking up of hardpacked soil followed by intermixing of the broken soil to overturn crop residue or other debris thereby creating a loose friable seedbed in which to plant. Conditioned soil provides a better environment for seed growth and promotes good soil-seed contact through which moisture and nutrients will flow.
Although wholesale conditioning of the entire field prior to planting is often practiced, heavily worked or overly conditioned land is prone to depletion of soil moisture and nutrient loss via erosion. More recently, conservation farming techniques have come into use to restrict tillage to only those areas of the soil which are to be planted. These methods are broadly referred to as minimal tillage or "no-till" farming and comprise conditioning of the soil and making a small opening for seed with reduced plowing. Although such no-till methods reduce soil erosion, they fail to sufficiently condition the soil for optimum seed germination and therefore crop yields are low. Since sides of the seedbeds are often left unworked, they insufficiently filter water and nutrients therethrough.
Whereas conventional operations required several passes through the field, one to till the ground, second to introduce fertilizer or compact the ground and a third to plant the seed, minimal tillage operations accomplish these discrete operations in a single pass. However the machines are unduly heavy and cumbersome. Further, since a number of separate operations such as planting, fertilizing and conditioning are combined within a single device, the agricultural implementation of that combination tends to become overly elongated, difficult to control, and extremely heavy. The weight of the overall machine often re-compacts the soil which has been conditioned. Also, combining a number of separate soil working implements onto a single machine tends to reduce the efficiency of each of the individual implements. For example, very often the machine is so large and heavy that the soil is insufficiently broken up and the seedbed is irregular or excessively compacted along the sides. When traversing rough or uneven ground the rigid nature of the prior art devices fail to compensate creating furrows or seedbeds which are nonuniform in depth.
In addition, overly long prior art no-till devices tend to accumulate trash or other crop residue and debris as it hangs up in front of the various subsoilers or coulter disks. The machine must be repeatedly stopped to allow manual removal of the debris. Finally, prior art devices tend to hang up when the subsoiler strikes an underground obstruction such as a rock or stump. In such situations the machine must be backed up to free the subsoiler of the underground debris resulting in a loss of time.
A need has therefore existed within the art which overcomes the disadvantages inherent in both conventional tillage practices as well as no-till practices.